i can feel the difference in my truck between octanes, it will barely run on 87 so i gotta run 93 or more

 

The engine is designed to spark at a certain temp. and most cars are lower compression which is 87 is all you'll ever need. As an example my friends dad has a 49 Merc with a crate502 and a Weiland blower pushing 800hp still on 87 due to the motor. Now on the other hand the Crotch-rockets out there that are high compression they do need, to safely say, 92+ octane.
Higher Compression = Higher Octane

http://auto.howstuffworks.com/fuel-e...question90.htm

Source: http://www.car-forums.com/s9/t28070.html
Octane DOES NOT clean anything. Octane in layman’s terms is a measure of resistance to detonation. Too high of an octane may actually burn too cool and create/increase carbon deposits in the combustion chamber, exhaust ports (including valves), exhaust and damage the cat.

Additive packages added to gasoline at the refinery, specifically detergents, can clean or keep clean fuel system and engine mechanical components. All gasoline sold in the USA has a minimum required amount of detergent by law. For most cars under most circumstances this is plenty of "cleaning". If you're concerned, run a bottle of Lucas fuel treatment through the engine (follow the directions) every oil change.

The biggest problem with gas in the US is not what comes from the refineries. It's the cleanliness of the tanker it's transported in and most importantly the underground tanks it's stored in at the gas station. Avoid the high dollar stations that move gas slowly. Purchase at the places that move it the fastest, which are usually the cheapest places in town. In many cases the gas is exactly the same gas from exactly the same truck, just different names and prices on the pump.

Also keep your tank as full as is reasonably possible at all times. The lower the the fuel level, the more space there is for condensation to form in the tank. Up north where you live, the cold of winter and the humid summers will fill (not literally) a gas tank with water. Same thing in the deep south where I live. Humidity, humidity, humidity. Even in the arid southwest, condensation will accumulate in an empty(ish) tank. Eight ounces of denatured alcohol every three months will take care of it for the most part and help keep your tank clean.


True story. A week or so ago the fuel pump on my '95 Dakota finally crapped out. Twelve years old and 240k+ miles on the original pump and tank, never been dropped, and when I drained it I let the gas and water seperate, just to see. Guess what? It had absolutely zero water and essentially no sediment. It's amazing what being cheap enough to do just a little preventative maintenance will do.


Edit: I knew after typing that much I'd forget something. Try not to fill your tank at a station within about 12 hours of their tanks being filled. As you can imagine having a tanker dump it's load causes some turbulence in the underground tank. This serves to stir up all the sh*t down there and if you fill up too soon, some of will get into your tank. The 12 hour cool off period gives it a chance to settle.
vwhobo

 

What we're trying to say is, if you can feel a noticeable difference in power between 87 and 93, then your engine must have a TON of KR. Since your engine was built to run on 87 (hence the low compression ratio)- if you have a lot of KR, then something is wrong- either you have a lot of carbon buildup, or your valve seals are leaking oil into the airway- or some other mechanical problem. In proper operating condition, your engine should perfectly fine on 87, and there should be little to no power difference by going with a higher octane- definitely not a noticeable difference.

This doesn't make sense to me either; the only time that octane really matters is under heavy load- so it should run perfectly fine any other time on any octane gas.